A controversial scientist, who failed in his attempts to clone a human in January, has met further scepticism over his latest cloning claims. US fertility doctor Panos Zavos says he has created a cloned embryo using tissue from dead people.
Experts said such actions would exploit the vulnerability of grieving people who had been bereaved.
But the Royal Society questioned "a lack of evidence" behind Dr Zavos' claims. Dr Zavos told a press conference in London he had successfully combined genetic material from three dead people with cow eggs to make embryos that were an identical copy of the deceased.
He said he took DNA from blood samples from an 11-year-old girl who had died three days earlier in a car crash.
The other corpses whose tissue he took included an18-month-old toddler who had died following surgery, and a 33-year-old man.
Two of the three experiments were successful, creating embryos that Dr Zavos claimed would be "potentially viable" if left to grow in the human womb.
Dr Zavos said he had not done this yet and had stopped the embryos' development at an early stage when cells begin to divide and multiply rapidly.
But said his current work was a major step forward showing this could be way to clone humans in the future.